The 3008 doesn't use a mag. catch retainer like a Sten, so the housing itself would be made slightly longer, front to back. Can't alter the front, because that is the limiting position for the front of the magazine. The rear of the housing would have to be shifted to the rear. This would be do-able, but the thought of cutting into a $2500 gun to permanently alter it to use $10 magazines instead of $85 ones leaves me a bit uneasy. Or, the welds could be cut, and a new magazine housing assembly fabricated and installed. Either way, I think it would be easier and more cost effective to just buy the 38u40 magazines.
Alternatively, measure a Sten mag, front to rear and compare it to the size a 38u40. Perhaps the rear of the Sten mag. could be thinned enough that the mag. could fit the 3008.